Well this is pretty cool. The advertising firm Chitika has come up with a live tracker that gives the average joe (yes, that’s you!) the ability to track what percentage of iPhones in use are running on AT&T’s network compared to Verizon’s. How does it manage to do that? Why, through its advertising network of course. So yeah, this is far from utterly scientific, but it’s still pretty intersesting.

So what does the data tell us? Well it would seem that just days after launch, nearly 4% of all iPhones in use are running on Verizon. Note that the percentages are based on a 24-hour rolling average and are updated on the hour.

The real question, though, is if AT&T customers are hopping over to Verizon in droves or if that data merely represents the obvious and significant increase in the total number of iPhones in use.

On that note, electronics reseller Gazelle is reporting that they’ve seen a marked increase in the number of Android devices users are turning in for either cash or trade-ins.

Gazelle, which has retail partners but primarily operates through its website, says it has received thousands of Droids following Verizon’s Jan. 11 announcement. The recent shipments have doubled the volume of Droid phones the company usually gets, according to Gazelle President and Chief Executive Israel Ganot. Droid trade-ins climbed even higher in the past week when Verizon began accepting pre-orders for the iPhone, says Ganot.